Gaussian process modeling for stochastic multi-fidelity simulators, with application to fire safety

To assess the possibility of evacuating a building in case of a fire, a standard method consists in simulating the propagation of fire, using finite difference methods and takes into account the random behavior of the fire, so that the result of a simulation is non-deterministic. The mesh fineness tunes the quality of the numerical model, and its computational cost. Depending on the mesh fineness, one simulation can last anywhere from a few minutes to several weeks. In this article, we focus on predicting the behavior of the fire simulator at fine meshes, using cheaper results, at coarser meshes. In the literature of the design and analysis of computer experiments, such a problem is referred to as multi-fidelity prediction. Our contribution is to extend to the case of stochastic simulators the Bayesian multi-fidelity model proposed by Picheny and Ginsbourger (2013) and Tuo et al. (2014)

Challenging Assumptions of Sustainable Corporate Entrepreneurship

We contribute to the holistic picture of the phenomenon SCE by adding an interpretative perspective, allowing us to critically challenge five assumptions that theoretically underlie its conceptualization. We challenged SCE’s assumptions that: employees have a common understanding and perception of sustainability and CE; that these understandings are in line with SCE theory; that the three dimensions of sustainability can be balanced; that the SCE-presumed link between the two concepts is feasible; and the objective that sustainability leads to CE. By doing so, we present implications for practitioners confronted with sustainability and CE, as well as for scholars researching in the field of SCE and the general relationship between sustainability and CE

Nocturnal nitrogen oxides at a rural mountain-site in south-western Germany

A new, two-channel instrument for simultaneous NO3 and N2O5 monitoring was used to make the first comprehensive set of nocturnal NOx measurements (NO, NO2, NO3 and N2O5) at the Taunus Observatory, a rural mountain site (Kleiner Feldberg) in South-western Germany. In May 2008, NO3 and N2O5 mixing ratios were well above the instrumental detection limit (a few ppt) on all nights of the campaign and were characterised by large variability. The concentrations of NO3, N2O5 and NO2 were consistent with the equilibrium constant, K2, defining the rates of formation and thermal dissociation of N2O5. A steady-state lifetime analysis is consistent with the loss of nocturnal NOx being dominated by the reaction of NO3 with volatile organic compounds in this forested region, with N2O5 uptake to aerosols of secondary importance. Analysis of a limited dataset obtained at high relative humidity indicated that the loss of N2O5 by reaction with water vapour is less efficient (>factor 3) than derived using laboratory kinetic data. The fraction of NOx present as NO3 and N2O5 reached ~20% on some nights, with night-time losses of NOx competing with daytime losses

Clandestins au secret. Contrôle et circulation de l’information dans les centres de rétention administrative français

Parmi les espaces d’internement destinés aux étrangers qui se multiplient aujourd’hui en Europe, les centres de rétention administrative présentent la particularité de se trouver directement au contact des sociétés occidentales, mais aussi de leurs espaces publics. Ces centres s’insèrent alors dans un dispositif plus général de détection des étrangers présents irrégulièrement sur le territoire des Etats Schengen. Il doivent à ce titre permettre de prélever sur eux une information favorisant leur éloignement du territoire ou tout au moins leur « traçabilité ». A travers l’exemple d’un centre de rétention français, cette contribution s’efforce d’analyser l’organisation de ce prélèvement de l’information, mais elle envisage également la manière dont cette organisation est infléchie voire déjouée par la possibilité d’un contact non formalisé et non maîtrisé des étrangers retenus avec l’espace public dont ils ont été retranchés, notamment à travers le transport de l’information par les équipiers de la Cimade présents au centre.The current development of detention camps for undocumented foreigners in the Schengen area underlines the specificity of « deportation camps », especially designed to manage the population of expelled foreigners formerly present on the territory of a member State. Settled inside European countries, those camps come in addition to the various devices created in order to track and detect undocumented foreigners. In that sense, deportation camps are part of an information-collecting apparatus. Through the example of a French « centre de retention », this contribution aims to analyse the organisation of that information collect. In this attempt, the impact of informal contacts of the detainees with the French national public sphere, and the role of the Cimade association in their development, shall particularly be examined

Les expulsés inexpulsables. Recompositions du contrôle des étrangers dans la France des années 1930

Parmi les institutions mises en place au cours du XXème siècle pour l'exercice d'une surveillance politique, le camp a connu des usages très divers. Il paraît d'autant plus nécessaire de le réinsérer dans l'agencement général de la surveillance qui lui donne sens. Si le camp apparaît à un moment donné dans les pratiques matérielles et discursives, c'est que, comme l'indique Foucault à propos de la prison, il a été sélectionné par le « diagramme », par la cartographie générale du pouvoir. Il f..